1. Field of the Invention
This invention relates to polymers of methyl vinyl ether, and, more particularly, to a process for the production of amorphous polymers of methyl vinyl ether which have a relatively high molecular weight and narrow molecular weight distribution.
2. Description of the Prior Art
The polymerization of alkyl vinyl ethers to form amorphous homopolymers is well known; see U.S. Pat. Nos. 2,104,000; 2,653,923; 2,799,669; 2,984,656; 3,017,260; 3,022,280; 3,023,198; 3,047,555; 3,080,352; and 3,332,924; C. E. Schildknecht Vinyl and Related Polymers (Wiley, 1952) page 602, and German Patent No. 2062213 (6/22/78).
Despite the availability of several commercial and laboratory processes for the production of alkyl vinyl ether homopolymers, there is still a need for improved processes which can provide high quality methyl vinyl ether homopolymers of predetermined molecular weight. However, methyl vinyl ether has a boiling point of only 5.5.degree. C., which is below room temperature, and therefore it is difficult to handle. Furthermore, methyl vinyl ether does not readily form homopolymers having high molecular weights and/or a narrow molecular weight distribution. Accordingly, it has been necessary to use very low operating temperatures, e.g. -40.degree. to -80.degree. C., for controlled cationic polymerization of Attempts to operate at temperatures in the vicinity of from 0.degree. C. to room temperature have not been very successful because of the difficulty of obtaining polymers with molecular weights sufficient for practical applications, such as adhesive compositions.
Accordingly, an object of this invention is to provide a novel and practical process for the production of amorphous homopolymers of methyl vinyl ether.
Another object of this invention is to provide an improved process for making methyl vinyl ether homopolymers which have relatively high molecular weights and a narrow molecular weight distribution.
Still another object herein is to provide a process which is carried out in the vicinity of room temperature.
Yet another object is to provide a process for making methyl vinyl ether polymers without the use of objectionable solvents.
A further object herein is to provide a batch process for the cationic polymerization of methyl vinyl ether monomer under practical reaction conditions, and, particularly, where the reaction exotherm can be readily controlled even at rapid reaction rates.
Among the other objects of the invention is to provide a methyl vinyl ether polymerization product in the form of a viscous, concentrated solution of amorphous polymeric methyl vinyl ether, in substantially residual methyl vinyl ether monomer as solvent, and wherein the polymer has a weight average molecular weight, MW.sub.w, above 110,000, preferably up to about 200,000, a number average molecular weight, MW.sub.n, of above 60,000, preferably up to about 100,000, with a molecular weight distribution, MW.sub.w, MW.sub.n,of less than 2.0.
These and other objects and features of the invention will be made apparent from the following more particular description of the invention.